Spectroscopy of inter-orbital spin-exchange interaction in 171Yb as a function of the magnetic field.
We load fermionic 171Yb atoms in a deep 3D optical lattice and perform precision spectroscopy on the ultra-narrow 1S0 - 3P0 transition. If two atoms in different spin states occupy the same lattice site they can be excited to two different mixed orbital states where the spin triplet state requires an orbital singlet state to fulfil the fermoinic antisymmetrization and vice versa. The energy difference between these two states defines a spin-exchange interaction relevant for the implementation of the Kondo lattie model with ultracild Yb atoms. We have determined this exchange interaction and find it to be anti-ferromagnetic and moderate in strength, which is an ideal starting point for further investigation of the Kondo lattice model with 171Yb.